Problem: Solve for $a$ : $24 = -1 + a$
Solution: Add $1$ to both sides: $ \begin{eqnarray} \\ \hphantom{24 {+ 1}} &\hphantom{=}& \hphantom{a} \\ 24 &=& -1 + a \\ \\ {+1} && {+1} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ 24 {+ 1} &=& a \\ \end{eqnarray} $ Simplify. $ a = 25$